I• T-33 (SILVER STAR MK 3 ) PITOT-STATIC SYSTEM CALIBRATION in Q F F T C THOMAS R. WOOD FORD Project Engineer ERIC P. HANSEN, Major, USAF Project Pilot FINAL REPORT 8 JUNE 1985 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AIR FORCE PLIHNr TEST CENTER KDWARDS A IR FORCE BASKE CALIFORNIA AIin FORCE SYSTiMS COMM AND STATES AIN FORCE .5 8 6 0 8 0 ," .. r .""-'-" -' I l~~...... . -,- ..... -.-.-.-_,--.-•.'.....•..."..""."."""."."'"" '"", ,-.
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"This technical report, T-33 (Silver Star MK 3) Pitot-Static System Calibration, was submitted under Job Order Number
2591A0 by the Commender, 6510th Test Wing, Edwards AFB,
California 93523.
This report has been reviewed by th e Office of Public
Affairs (AFFTC/PA) and is releasable to the National Technical
Information Service (NTIS). At NTIS, it will be available tothe general public, including foreign nationals.
Prepared by: This report has been reviewed
and is approved for publication:
THOMAS R. WOODFORD MICHAEL . EM SON
Project Engineer Lieutenant Colcnel, USAF
Director, T-46A Combir.•dTe3t Force
JEX .'BEUTLER III
Colonel, USAF
Acting6Come stGroup
SATEN
Colonel, USAF
Commander, 6510th Test Wing
Major General, USAF
Comnmander
When U.S. Government drawings, specifications, or any other
data are used for any purpose other than a definitely relatedgovernment procurement operation, the government thereby incursno responsibility nor any obligation ihatsoever; and the fact
that the government nay haie foraul3ted, furnished or in any
way supplied the said drawings, specifications, or any other
data is not to be regarded by implication or otherwise, as in
any manner l icensing th e holder or any other person or
corporation or conveying any right or permission to
manufacture, use, or sell any patentend invention that may in
This report presents the results of pltot-static system calibration testsperformed on T-33 (Silver Star W 3), civil registration number Nt3TB.The T-33 pitot-static system 'was calibrated in order to use the T-33 as a pacer forthe T-46A oitot-static systed calibration tests to be performed during the T-46ADevelopment Test and Evaluation Program. AX e test aircraft will perform satisfactorilyas a pacer, 4owever,9periedic checks on the pitot-static system's accuracy shouldbe performed. t., ,eA:,
20 DISTRISUTIONIAVAILABILITY GA ABSTRACT 21 ABSTRACT SECUMIT- CLASSIFICATION
UNCLASIFIECOUNLI•ITED SAME AS RPT. ] C-,C uS UNCLASSIFIED
22M NAME OV RESPONSIBLE INOIVIDUAL M TIELEPHONE NUMBER 22c OFFICE SYMBOL
Thoams R. oodford I*WAmCoehoas . Wodfrd(805) 277-045.8 TEVT
DO FORM 1473,83 APR 1 DIlON OF I JAN 73 IS OBOLETE
The T-33 (Silver Star MK 3) pitot-static systemcalibration tests were performed in support of the T-46ADevelopment Test and Evaluation (DT&E) program. The T-46A test
program waz directed by th e T-46ASystem Program Office(ASD/AFG) of th e Aeronautical Systems Division, Wright-
Patterson AFB, Ohio. The T-33 pitot-static system calibration
was required to enable the T-33 to function as a pacer fo r the
pitot-static system calibration of the T--6A.
The author thanks Mr. Frank Brown and Mr. Al DeAnda fortheir technical assistance. The project pilots were Major Eric
Tower fly-by and pacer data vere used to deteiinine theposition error. Reference 1 was used as a guideline for the
tests. Th e tower fly-bys were conducted using the AFFTC tower
fly-by facility. The position error was obtained from thedifference between the T-33 test aircraft's instrumentcorrected altimeter reading and th e aircraft's pressure
altitude determined by tower stadiametric observation.
Pacer data was obtained with an AFFTC calibrated pacer
aircraft (T-38A, S/N 70-1575). Both stabilized and
unstabilized pace techniques were used. During stabilized pace
the T-38 pacer flew in close formetion with the T-33 test
aircraftmaintaining
the same altitude and airspeed duringstabilized straight-and-level flight. The position error was
obtained from the difference between the T-33 test aircraft's
instrument corrected altimeter reading and the T-38 pacer'sinstrument and position error corrected altimeter reading.
An unstabilized pace technique was used to obtain data atspeeds lower than the T-38 pacer could maintain in stable one-g
straight-and-level flight (approximately 170 KCAS). The T-38pacer 3et up at the same altitude behind and to the side of theT-33 test aircraft. The T-33 stabilized at the test airspeed(less than 170 KCAS) and the T-38 pacer stabilized atapproximately 17 0 KCAS. Airspeed and altimeter readings were
taken as the T-38 pacer overaook the T-33 test aircraft at thesame altitude. The position error 2 obtained from thealtimeter difference as with the stabilized pect technique. Alldata from both aircraft were hand recorded. The front and rear
cockpit instrument readings in the pacer and the front and reartest aircraft airspeed readings were each -veraged to improveaccuracy.
DATA ANALYSIS
The altitude pozition errcrs determined from the testswere used for data analysis. Low resolution of the airspeed
indicators with respect to the small airspeed pusition errorresulted in large scatter in the position error data determinedfrom the airspeed difference during stabilized pace. Thereforethe airspeed difference was not used for analysis. The
position error pressure coefficient ZAPf/qci : position errorpressure/indicated differential pressure? was calculated frim
the altitude position error and is shown in Figure 2. rhe
scatter in the low speed data (especially the 20 degree flaps
data) was largely due to the degraded accuracy of the
Accurate calibration data were obtained fo r th e T-33(Silver Star MK 3), civil registration N83TB, by the tower fly-by and pacer techniques. The accurate calibration of th e
pitot-static system will allow the use of the T-33 as a paceraircraft for support of th e T-46A Development Test and
Evaluation Program. In order to insure the continued accuracy
of the pitot-static system calibration, periodic checks shou]d
be performed.
1. A limited number of tower fly-by passes
should be performed periodically to verify
the pitot-static system accuracy. (page 12)
2. The accuracy of tVe airspeed indicators and
altimeters should be checked periodically to
insure accurate pito' static system data.(page 12)
1. DeAnda, Albert G., AFFTC Standard Airspeed CalibrationProcedures, AFFTC-TIH-81-5, Air Force Flight Test Center,Edwards AFB, California, June 1981.
2. Hart, Ronald E., Airspeed Calibration Reduction Program forthe ZiO Computer, Office Memo, Air Force Flight Test Center,Edwards AFB, California, September 1984.